1. Field of the Invention
This invention relates generally to digital data storage apparatus, and relates more particularly to an automatic disc changer apparatus for selecting and loading any one of a plurality of digital data discs onto multiple data input/output devices.
2. Description of the Relevant Art
One relatively new form of storing digital data is optically based, in which digital data is stored on and retrieved from a data disc in an optically discernible form using a laser read/write head. In common use today are audio compact discs and players that recreate audio sounds based upon digitized audio information stored on the audio compact discs. The audio compact disc is a rigid plastic disc of about 4.7 inches in diameter with a concentric 0.6 inch diameter center hole. Also in use today are optically based disc systems for use as digital storage devices for computers, known as CD ROM devices, where CD ROM stands for compact disc read-only memory. Other storage devices have means for both storing data onto and retrieving data from the data discs.
Most currently available optical data systems are capable of accessing only a single data disc at a time, which must be loaded by hand. In some compact disc players, a drawer extends outward to accept an audio compact disc to be played, then the drawer retracts into the body of the compact disc player to load the compact disc onto a spindle of the player. In other compact disc players, a lid or cover is lifted, the audio compact disc is inserted into the compact disc player, and the lid or cover is then closed to bring the compact disc into engagement with the spindle. In operation, the spindle engages the center hole and rotates the disc, while the laser head tracks radially to read the digitally stored data in a spiral pattern.
Some compact disc players are available that can access multiple compact discs. Up to a dozen or so compact discs are loaded into a magazine, which is then inserted into the compact disc player. When a compact disc is selected for play, a loading mechanism loads the disc onto the play mechanism of the disc player. When another compact disc is selected, one disc must be unloaded from the disc player and reinserted into the magazine before the next disc can be loaded onto the disc player.